afaik it isnt fel fire that gets infused with their fire spells, its fel magic, so it should be added to spells of all schools, would be nice to have a reason to bother with getting it as affliction. it wouldnt even have to be a change of color, it could just as easily be a change in the way beam looks, like changing into something like a thicker version of MG with dark energy "spikes" coming out of your hands when you cant it. could easily be a mix of the diablo 3 disintegrate beam(depending on rune ofc) and the current MG beam, i think that would look cool.